Small tank: this serpae tetra is a bully

[LooksLater]

Just look into each shrimp's requirements, as long as they are happy with the pH etc that you offer, and will not crossbreed, you should be fine. Some say the bigger shrimp like amanos will out-compete dwarf shrimp for food, but we keep amanos in with our red cherries and haven't had any trouble.

Here's a good chart for what will/won't crossbreed...

http://www.planetinverts.com/Shrimp-Chart3.jpg?sid=E783ACA487AAB396558E79AA6AE19A1D

[CrazyCatPeekin]

I've got a couple of amanos in with my yellow shrimp and haven't had any problems at all.

+1 to mnemennoi's stocking suggestions. I personally like the look of a nice group of very small fish in a small tank. I don't think he mentioned Endler's which are very colorful and would also make a nice choice. (Someone else may have said so earlier.) Just make sure if you decide on them that you get males only or you'll be overrun with babies.

I've had habrosus corys in with my red shrimp for some time now and haven't noticed any issues. In fact, I actually just noticed a boom in the number of babies in that tank. There are also hastatus or pygmaeus corydoras which also stay very small. As long as your gravel is not sharp or rough, I think they would be ok.

[mnemenoi]

Amano can do well with most of the neocardinia family (Red Cherry, snowball, blue, yellow), but they are all very closely related and can interbreed with the other color variants. Caridinia are the crystal red/black (CRS/CBS) and there are many grades of how pure and colored they are. It also has Tiger shrimp and their varieties and some bee shrimp. They do best in softer water and are a bit more difficult. There are the Sulawesi that are hard as well, but prefer very hard water. Then there are the oddballs, like our native ghost/glass shrimp, Fan/bamboo shrimp, and macrobranchia which are larger and can be predatory. I would recommend one of the local breeders for whatever shrimp you find that you prefer, they are far cheaper and have far more reliable stock then acquiring them elsewhere. Tim (armthehomeless), Heipsta, and Bikeguru all have terrific stock and wonderful prices when compared to anything else.

[aquabee]

Definitely the habrosus or pygmy cory would be nice since they're dwarf fish. But I definitely agree with a neutral sand substrate, one that won't alter your pH. Green neon tetras (the micro neons) are a wonderful fish for a nano tank and are very hardy. They're bright and active, not aggressive, shrimp friendly, and I think your kids would enjoy them a lot. HAW (Houston Aquarium Warehouse) is the main supplier of these fish locally.